Communication management system with line status notification for key switch emulation

1. A telephony system comprising a control unit and a plurality of telephony stations interconnected by a packet switched network, the control unit being coupled to a telephony service provider network by a plurality of outside telephone lines; a first of the telephony stations comprising: a network interface for communicating over the packet switched network; means for establishing a logical channel to support a media session over the packet switched network with an endpoint, selected from a group of endpoints consisting of the control unit and another of the plurality of telephony stations, for the exchange of real time streaming media with the endpoint during a media session; means for receiving microphone input and generating compressed digital audio frames representative thereof for transmission to the endpoint during the media session and for receiving compressed digital audio frames from the endpoint and driving a speaker to output audio in response thereto; a user interface comprising a plurality of indicators, each being associated with one of a plurality of selection buttons, at least one of the plurality of indicators being associated with one of the plurality of outside telephone lines, the indicator indicating a status of the outside telephone line, the status being one of “available” and “in-use”; the selection button associated with such indicator being effective to initiate a real time communication session to a remote device utilizing such outside telephone line when activated by a user; a status application comprising a multicast client, the multicast client: obtaining a multicast group address of a multicast group associated with the control unit; joining the multicast group; and updating the status of the indicator associated with the outside telephone line between the “available” and “in-use” status in response to receiving a multicast status message addressed to the multicast group address and identifying the outside telephone line and its status.

2. The telephony system of claim 1 , wherein: at least one of the plurality of indicators is associated with a second of the plurality of telephony stations, the indicator indicating a status of the second of the plurality of telephony stations, the status being one of “on-hook” and “off-hook”; the selection button associated with the indicator being effective to initiate a real time communication session to the second of the plurality of telephony stations when activated by a user; and the status application updates the status of the indicator associated with second of the plurality of telephony stations between the “on-hook” and “off-hook” status in response to receiving a multicast status message addressed to the multicast group address and identifying the second of the plurality of telephony stations.

3. The telephony system of claim 2 , wherein the status application further comprises a multicast host, the multicast host: sending a multicast status message addressed to the multicast group address; and wherein the multicast status message identifies the first of the telephony stations and includes an indication of the status of the first of the telephony stations, the status being one of “on-hook” and “off-hook”.

4. The real time communication device of claim 3 , wherein: the multicast group address is an IP multicast address distinct from an IP address of the control unit, an IP address of the first of the telephony stations, and an IP address of the second of the telephony stations.

5. The telephony system of claim 4 , wherein the multicast host further sends a multicast status message in response to passage of a time duration during following sending of a previous multicast status message even if there has been change in status of the first of the telephony stations.

6. The telephony system of claim 4 , wherein the multicast host further sends a multicast status message in response to receiving a status refresh request on the multicast group address.